Prior to receiving any services from a network operator, a roaming wireless device must select a network from one or more available networks. Multi-RAT (Multi Radio Access Technology) capable wireless devices operating in regions with overlaying Multi-RAT networks pose a further problem for roaming. For example, a Multi-RAT wireless device capable of supporting CDMA (Code Division Multiple Access) and GSM (Global System for Mobile communications) radio access technologies may roam to a region covered by one or more CDMA networks and one or more GSM networks.
It may be that, for example, due to roaming agreements between the operator of the wireless device's home network and the network operator(s) of the available networks in the wireless device's current geographic location, CDMA is the current preferred RAT in the wireless device's current geographic location. However, in another geographic location, for example, in another country, the preferred RAT may be GSM.
Since roaming agreements can change quite dynamically, a hardcoded list stored on a wireless device during production or sale is typically not an ideal solution. Furthermore, since a multi-RAT capable wireless device is capable of operating according to two or more standards respectively associated with the two or more RATs with which it is capable of operating, it is not typically possible to use standard specific mechanisms for optimal roaming.
Many wireless devices are capable of both voice and data communication. However, not all of the networks that are available in the current location of a wireless device may support both voice and data communications. For example, an older legacy network may be available that only supports voice calling, but cannot support data communications, such as e-mail or web browsing.